The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs and may result in higher taxes when the fund’s shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 10%.

Putnam Retirement Advantage 2060 Fund seeks capital appreciation and current income consistent with a decreasing emphasis on capital appreciation and an increasing emphasis on current income as it approaches its target date.

The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 101 of the fund’s prospectus, in Appendix A to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI).

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. The example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Investments

The fund’s asset allocation strategy may be attractive to investors who plan to retire or otherwise intend to begin making periodic withdrawals of their investments in or about 2060 (the target date). The fund is designed to provide diversification among different asset classes by investing its assets in other Putnam mutual funds, referred to as underlying funds.

The fund’s target allocations among asset classes and underlying funds will increasingly emphasize capital preservation and income over time and will change gradually based on the number of remaining years until the fund’s target date, as shown in the predetermined “glide path” in the chart under “What are the funds’ and each underlying fund’s main investment strategies and related risks?” Putnam Investment Management, LLC (“Putnam Management”) adjusts these allocations at the end of each calendar quarter based on the glide path.

The following table presents your fund’s approximate allocations to each asset class and underlying fund as of December 31, 2022 and its projected approximate allocations to those asset classes and underlying funds as of December 31, 2023. By comparing the percentage allocations of your fund in the table, you can see how its allocations are expected to change during the one-year period beginning on December 31, 2022.

The table also shows the approximate allocations of other Putnam Retirement Advantage Funds, which are designed for investors with different target retirement dates. Over a five-year period, each fund’s allocations will gradually change to resemble the allocations of the fund with the next earliest target date. The table illustrates how a fund’s allocations are expected to change over time to increasingly emphasize capital preservation and income.

The fund’s target allocations may differ from the allocations shown in the table. We may change the glide path, the fund’s target allocations, and the underlying funds in which it invests at any time, although we expect these changes to be infrequent and generally in response to longer-term structural changes (i.e., in the average retirement age or life expectancy) that lead the fund’s portfolio managers to determine that a change is advisable. We assume investors will begin gradual withdrawals from the

fund at around the target date. Near the end of the target date year, the fund’s target allocations will correspond to those of Putnam Retirement Advantage Maturity Fund (Maturity Fund), a fund that seeks as high a rate of current income as Putnam Management believes is consistent with preservation of capital, and the fund will be merged into Maturity Fund. More information about Maturity Fund is available in this prospectus beginning on page 74, and more information about the underlying funds (which are not offered by this prospectus) is included under “What are the funds’ and each underlying fund’s main investment strategies and related risks?”.

It is important to understand that you can lose money by investing in the fund. Losses may occur near, at or after the target date. There is no guarantee that the fund will provide adequate income at and through an investor’s retirement.

The fund’s allocation of assets among asset classes and the underlying funds may hurt performance.

The fund invests in underlying funds and indirectly bears expenses related to the underlying funds. However, Putnam Management has contractually agreed to waive fees, reimburse expenses of, or reimburse the fund through at least December 30, 2025 in an amount equal to the fund’s acquired fund fees and expenses (i.e., the fees and expenses incurred by the fund as a result of its investments in the underlying funds). Putnam Management also has contractually agreed to waive fees and/or reimburse expenses of each class of shares of the fund through at least December 30, 2025 in an amount sufficient to result in total annual fund operating expenses for class A, C, R, R3, R4, R5, R6 and Y shares of the fund (exclusive of certain fees and expenses, including distribution fees (12b-1 fees)) that equal 0.55%, 0.55%, 0.70%, 0.70%, 0.70%, 0.55%, 0.45%, and 0.55%, respectively, of the fund’s average net assets. Although Putnam Management serves as the investment adviser of the underlying funds, an underlying fund may change its investment program or policies without the fund’s approval, which could require the fund to reduce or eliminate its allocation to the underlying fund at an unfavorable time.

The fund also bears the following risks associated with the underlying funds:

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the underlying funds will produce the intended outcome or that the investments we select for the underlying funds will perform as well as other securities that were not selected for the underlying funds. We, or the underlying funds’ other service providers, may experience disruptions or operating errors that could negatively impact the underlying funds. If the quantitative models or data that are used in managing an underlying fund prove to be incorrect or incomplete, investment decisions made in reliance on the models or data may not produce the desired results and the fund may realize losses.

An underlying fund’s allocation of assets among asset classes may hurt performance. The value of investments in the underlying funds’ portfolios may fall or fail to rise over extended periods of time for a variety of reasons, including general economic,

political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the underlying funds’ portfolio holdings. The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the underlying funds invest and exacerbate other risks that apply to the underlying funds. These effects could negatively impact the underlying funds’ performance and lead to losses on your investment in the fund. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. These risks are generally greater for small and midsize companies.

Bond investments are subject to interest rate risk, which is the risk that the value of the underlying funds’ bond investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the underlying funds’ bond investments may default on payment of interest or principal. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds (sometimes referred to as “junk bonds”), which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Default risk is generally higher for non-qualified mortgages. Mortgage-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. The underlying funds may have to invest the proceeds from prepaid investments, including mortgage- and asset-backed investments, in other investments with less attractive terms and yields.

The value of international investments traded in foreign currencies may be adversely impacted by fluctuations in exchange rates. International investments, particularly investments in emerging markets, may carry risks associated with potentially less stable economies or governments (such as the risk of seizure by a foreign government, the imposition of currency or other restrictions, or high levels of inflation), and may be or become illiquid.

Real estate investment trusts (REITs), which pool investors’ funds for investment primarily in income-producing real estate properties or real estate-related loans (such as mortgages), are subject to the risks associated with owning, operating, and financing real estate, including economic downturns that have an adverse impact on real estate markets. Convertible securities combine the investment characteristics of bonds and common stocks and include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk.

Putnam Dynamic Asset Allocation Equity Fund and Putnam Short Term Investment Fund may use, and each other underlying fund typically uses to a significant extent, derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and investment purposes (although, in the case of Putnam Short Term Investment Fund, they do not represent a primary focus of the fund). Underlying funds that use derivatives to increase investment exposure are riskier than underlying funds that do not employ investment leverage. The value of derivatives may move in unexpected ways due to unanticipated market movements, the use of leverage, imperfect correlation between the derivative instrument and the reference asset, or other factors, especially in unusual market conditions, and volatility in the value of derivatives could adversely impact the underlying fund’s returns, obligations and exposures. Derivatives are also subject to other risks, including liquidity risk (e.g., liquidity demands arising from the requirement to make payments to a derivative counterparty), operational risk (e.g., settlement issues or system failures), and legal risk (e.g., insufficient legal documentation or contract enforceability issues). Derivatives also involve the risk that an underlying fund may be unable to terminate or sell derivatives positions when it wants to and that the other party to the instrument may fail to meet its obligations. The risk of a party failing to meet its obligations may increase if the underlying fund has significant investment exposure to that counterparty.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.

Putnam Retirement Advantage 2055 Fund seeks capital appreciation and current income consistent with a decreasing emphasis on capital appreciation and an increasing emphasis on current income as it approaches its target date.

The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 101 of the fund’s prospectus, in Appendix A to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI).

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. The example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Investments

The fund’s asset allocation strategy may be attractive to investors who plan to retire or otherwise intend to begin making periodic withdrawals of their investments in or about 2055 (the target date). The fund is designed to provide diversification among different asset classes by investing its assets in other Putnam mutual funds, referred to as underlying funds.

The fund’s target allocations among asset classes and underlying funds will increasingly emphasize capital preservation and income over time and will change gradually based on the number of remaining years until the fund’s target date, as shown in the predetermined “glide path” in the chart under “What are the funds’ and each underlying fund’s main investment strategies and related risks?” Putnam Investment Management, LLC (“Putnam Management”) adjusts these allocations at the end of each calendar quarter based on the glide path.

The following table presents your fund’s approximate allocations to each asset class and underlying fund as of December 31, 2022 and its projected approximate allocations to those asset classes and underlying funds as of December 31, 2023. By comparing the percentage allocations of your fund in the table, you can see how its allocations are expected to change during the one-year period beginning on December 31, 2022.

The table also shows the approximate allocations of other Putnam Retirement Advantage Funds, which are designed for investors with different target retirement dates. Over a five-year period, each fund’s allocations will gradually change to resemble the allocations of the fund with the next earliest target date. The table illustrates how a fund’s allocations are expected to change over time to increasingly emphasize capital preservation and income.

The fund’s target allocations may differ from the allocations shown in the table. We may change the glide path, the fund’s target allocations, and the underlying funds in which it invests at any time, although we expect these changes to be infrequent and generally in response to longer-term structural changes (i.e., in the average retirement age or life expectancy) that lead the fund’s portfolio managers to determine that a change is advisable. We assume investors will begin gradual withdrawals from the

fund at around the target date. Near the end of the target date year, the fund’s target allocations will correspond to those of Putnam Retirement Advantage Maturity Fund (Maturity Fund), a fund that seeks as high a rate of current income as Putnam Management believes is consistent with preservation of capital, and the fund will be merged into Maturity Fund. More information about Maturity Fund is available in this prospectus beginning on page 74, and more information about the underlying funds (which are not offered by this prospectus) is included under “What are the funds’ and each underlying fund’s main investment strategies and related risks?”.

It is important to understand that you can lose money by investing in the fund. Losses may occur near, at or after the target date. There is no guarantee that the fund will provide adequate income at and through an investor’s retirement.

The fund’s allocation of assets among asset classes and the underlying funds may hurt performance.

The fund invests in underlying funds and indirectly bears expenses related to the underlying funds. However, Putnam Management has contractually agreed to waive fees, reimburse expenses of, or reimburse the fund through at least December 30, 2025 in an amount equal to the fund’s acquired fund fees and expenses (i.e., the fees and expenses incurred by the fund as a result of its investments in the underlying funds). Putnam Management also has contractually agreed to waive fees and/or reimburse expenses of each class of shares of the fund through at least December 30, 2025 in an amount sufficient to result in total annual fund operating expenses for class A, C, R, R3, R4, R5, R6 and Y shares of the fund (exclusive of certain fees and expenses, including distribution fees (12b-1 fees)) that equal 0.55%, 0.55%, 0.70%, 0.70%, 0.70%, 0.55%, 0.45%, and 0.55%, respectively, of the fund’s average net assets. Although Putnam Management serves as the investment adviser of the underlying funds, an underlying fund may change its investment program or policies without the fund’s approval, which could require the fund to reduce or eliminate its allocation to the underlying fund at an unfavorable time.

The fund also bears the following risks associated with the underlying funds:

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the underlying funds will produce the intended outcome or that the investments we select for the underlying funds will perform as well as other securities that were not selected for the underlying funds. We, or the underlying funds’ other service providers, may experience disruptions or operating errors that could negatively impact the underlying funds. If the quantitative models or data that are used in managing an underlying fund prove to be incorrect or incomplete, investment decisions made in reliance on the models or data may not produce the desired results and the fund may realize losses.

An underlying fund’s allocation of assets among asset classes may hurt performance. The value of investments in the underlying funds’ portfolios may fall or fail to rise over extended periods of time for a variety of reasons, including general economic,

political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the underlying funds’ portfolio holdings. The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the underlying funds invest and exacerbate other risks that apply to the underlying funds. These effects could negatively impact the underlying funds’ performance and lead to losses on your investment in the fund. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. These risks are generally greater for small and midsize companies.

Bond investments are subject to interest rate risk, which is the risk that the value of the underlying funds’ bond investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the underlying funds’ bond investments may default on payment of interest or principal. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds (sometimes referred to as “junk bonds”), which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Default risk is generally higher for non-qualified mortgages. Mortgage-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. The underlying funds may have to invest the proceeds from prepaid investments, including mortgage- and asset-backed investments, in other investments with less attractive terms and yields.

The value of international investments traded in foreign currencies may be adversely impacted by fluctuations in exchange rates. International investments, particularly investments in emerging markets, may carry risks associated with potentially less stable economies or governments (such as the risk of seizure by a foreign government, the imposition of currency or other restrictions, or high levels of inflation), and may be or become illiquid.

Real estate investment trusts (REITs), which pool investors’ funds for investment primarily in income-producing real estate properties or real estate-related loans (such as mortgages), are subject to the risks associated with owning, operating, and financing real estate, including economic downturns that have an adverse impact on real estate markets. Convertible securities combine the investment characteristics of bonds and common stocks and include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk.

Putnam Dynamic Asset Allocation Equity Fund and Putnam Short Term Investment Fund may use, and each other underlying fund typically uses to a significant extent, derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and investment purposes (although, in the case of Putnam Short Term Investment Fund, they do not represent a primary focus of the fund). Underlying funds that use derivatives to increase investment exposure are riskier than underlying funds that do not employ investment leverage. The value of derivatives may move in unexpected ways due to unanticipated market movements, the use of leverage, imperfect correlation between the derivative instrument and the reference asset, or other factors, especially in unusual market conditions, and volatility in the value of derivatives could adversely impact the underlying fund’s returns, obligations and exposures. Derivatives are also subject to other risks, including liquidity risk (e.g., liquidity demands arising from the requirement to make payments to a derivative counterparty), operational risk (e.g., settlement issues or system failures), and legal risk (e.g., insufficient legal documentation or contract enforceability issues). Derivatives also involve the risk that an underlying fund may be unable to terminate or sell derivatives positions when it wants to and that the other party to the instrument may fail to meet its obligations. The risk of a party failing to meet its obligations may increase if the underlying fund has significant investment exposure to that counterparty.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.

Putnam Retirement Advantage 2050 Fund seeks capital appreciation and current income consistent with a decreasing emphasis on capital appreciation and an increasing emphasis on current income as it approaches its target date.

The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 101 of the fund’s prospectus, in Appendix A to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI).

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. The example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Investments

The fund’s asset allocation strategy may be attractive to investors who plan to retire or otherwise intend to begin making periodic withdrawals of their investments in or about 2050 (the target date). The fund is designed to provide diversification among different asset classes by investing its assets in other Putnam mutual funds, referred to as underlying funds.

The fund’s target allocations among asset classes and underlying funds will increasingly emphasize capital preservation and income over time and will change gradually based on the number of remaining years until the fund’s target date, as shown in the predetermined “glide path” in the chart under “What are the funds’ and each underlying fund’s main investment strategies and related risks?” Putnam Investment Management, LLC (“Putnam Management”) adjusts these allocations at the end of each calendar quarter based on the glide path.

The following table presents your fund’s approximate allocations to each asset class and underlying fund as of December 31, 2022 and its projected approximate allocations to those asset classes and underlying funds as of December 31, 2023. By comparing the percentage allocations of your fund in the table, you can see how its allocations are expected to change during the one-year period beginning on December 31, 2022.

The table also shows the approximate allocations of other Putnam Retirement Advantage Funds, which are designed for investors with different target retirement dates. Over a five-year period, each fund’s allocations will gradually change to resemble the allocations of the fund with the next earliest target date. The table illustrates how a fund’s allocations are expected to change over time to increasingly emphasize capital preservation and income.

The fund’s target allocations may differ from the allocations shown in the table. We may change the glide path, the fund’s target allocations, and the underlying funds in which it invests at any time, although we expect these changes to be infrequent and generally in response to longer-term structural changes (i.e., in the average retirement age or life expectancy) that lead the fund’s portfolio managers to determine that a change is advisable. We assume investors will begin gradual withdrawals from the

fund at around the target date. Near the end of the target date year, the fund’s target allocations will correspond to those of Putnam Retirement Advantage Maturity Fund (Maturity Fund), a fund that seeks as high a rate of current income as Putnam Management believes is consistent with preservation of capital, and the fund will be merged into Maturity Fund. More information about Maturity Fund is available in this prospectus beginning on page 74, and more information about the underlying funds (which are not offered by this prospectus) is included under “What are the funds’ and each underlying fund’s main investment strategies and related risks?”.

It is important to understand that you can lose money by investing in the fund. Losses may occur near, at or after the target date. There is no guarantee that the fund will provide adequate income at and through an investor’s retirement.

The fund’s allocation of assets among asset classes and the underlying funds may hurt performance.

The fund invests in underlying funds and indirectly bears expenses related to the underlying funds. However, Putnam Management has contractually agreed to waive fees, reimburse expenses of, or reimburse the fund through at least December 30, 2025 in an amount equal to the fund’s acquired fund fees and expenses (i.e., the fees and expenses incurred by the fund as a result of its investments in the underlying funds). Putnam Management also has contractually agreed to waive fees and/or reimburse expenses of each class of shares of the fund through at least December 30, 2025 in an amount sufficient to result in total annual fund operating expenses for class A, C, R, R3, R4, R5, R6 and Y shares of the fund (exclusive of certain fees and expenses, including distribution fees (12b-1 fees)) that equal 0.55%, 0.55%, 0.70%, 0.70%, 0.70%, 0.55%, 0.45%, and 0.55%, respectively, of the fund’s average net assets. Although Putnam Management serves as the investment adviser of the underlying funds, an underlying fund may change its investment program or policies without the fund’s approval, which could require the fund to reduce or eliminate its allocation to the underlying fund at an unfavorable time.

The fund also bears the following risks associated with the underlying funds:

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the underlying funds will produce the intended outcome or that the investments we select for the underlying funds will perform as well as other securities that were not selected for the underlying funds. We, or the underlying funds’ other service providers, may experience disruptions or operating errors that could negatively impact the underlying funds. If the quantitative models or data that are used in managing an underlying fund prove to be incorrect or incomplete, investment decisions made in reliance on the models or data may not produce the desired results and the fund may realize losses.

An underlying fund’s allocation of assets among asset classes may hurt performance. The value of investments in the underlying funds’ portfolios may fall or fail to rise over extended periods of time for a variety of reasons, including general economic,

political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the underlying funds’ portfolio holdings. The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the underlying funds invest and exacerbate other risks that apply to the underlying funds. These effects could negatively impact the underlying funds’ performance and lead to losses on your investment in the fund. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. These risks are generally greater for small and midsize companies.

Bond investments are subject to interest rate risk, which is the risk that the value of the underlying funds’ bond investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the underlying funds’ bond investments may default on payment of interest or principal. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds (sometimes referred to as “junk bonds”), which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Default risk is generally higher for non-qualified mortgages. Mortgage-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. The underlying funds may have to invest the proceeds from prepaid investments, including mortgage- and asset-backed investments, in other investments with less attractive terms and yields.

The value of international investments traded in foreign currencies may be adversely impacted by fluctuations in exchange rates. International investments, particularly investments in emerging markets, may carry risks associated with potentially less stable economies or governments (such as the risk of seizure by a foreign government, the imposition of currency or other restrictions, or high levels of inflation), and may be or become illiquid.

Real estate investment trusts (REITs), which pool investors’ funds for investment primarily in income-producing real estate properties or real estate-related loans (such as mortgages), are subject to the risks associated with owning, operating, and financing real estate, including economic downturns that have an adverse impact on real estate markets. Convertible securities combine the investment characteristics of bonds and common stocks and include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk.

Putnam Dynamic Asset Allocation Equity Fund and Putnam Short Term Investment Fund may use, and each other underlying fund typically uses to a significant extent, derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and investment purposes (although, in the case of Putnam Short Term Investment Fund, they do not represent a primary focus of the fund). Underlying funds that use derivatives to increase investment exposure are riskier than underlying funds that do not employ investment leverage. The value of derivatives may move in unexpected ways due to unanticipated market movements, the use of leverage, imperfect correlation between the derivative instrument and the reference asset, or other factors, especially in unusual market conditions, and volatility in the value of derivatives could adversely impact the underlying fund’s returns, obligations and exposures. Derivatives are also subject to other risks, including liquidity risk (e.g., liquidity demands arising from the requirement to make payments to a derivative counterparty), operational risk (e.g., settlement issues or system failures), and legal risk (e.g., insufficient legal documentation or contract enforceability issues). Derivatives also involve the risk that an underlying fund may be unable to terminate or sell derivatives positions when it wants to and that the other party to the instrument may fail to meet its obligations. The risk of a party failing to meet its obligations may increase if the underlying fund has significant investment exposure to that counterparty.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.

Putnam Retirement Advantage 2045 Fund seeks capital appreciation and current income consistent with a decreasing emphasis on capital appreciation and an increasing emphasis on current income as it approaches its target date.

The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 101 of the fund’s prospectus, in Appendix A to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI).

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. The example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Investments

The fund’s asset allocation strategy may be attractive to investors who plan to retire or otherwise intend to begin making periodic withdrawals of their investments in or about 2045 (the target date). The fund is designed to provide diversification among different asset classes by investing its assets in other Putnam mutual funds, referred to as underlying funds.

The fund’s target allocations among asset classes and underlying funds will increasingly emphasize capital preservation and income over time and will change gradually based on the number of remaining years until the fund’s target date, as shown in the predetermined “glide path” in the chart under “What are the funds’ and each underlying fund’s main investment strategies and related risks?” Putnam Investment Management, LLC (“Putnam Management”) adjusts these allocations at the end of each calendar quarter based on the glide path.

The following table presents your fund’s approximate allocations to each asset class and underlying fund as of December 31, 2022 and its projected approximate allocations to those asset classes and underlying funds as of December 31, 2023. By comparing the percentage allocations of your fund in the table, you can see how its allocations are expected to change during the one-year period beginning on December 31, 2022.

The table also shows the approximate allocations of other Putnam Retirement Advantage Funds, which are designed for investors with different target retirement dates. Over a five-year period, each fund’s allocations will gradually change to resemble the allocations of the fund with the next earliest target date. The table illustrates how a fund’s allocations are expected to change over time to increasingly emphasize capital preservation and income.

The fund’s target allocations may differ from the allocations shown in the table. We may change the glide path, the fund’s target allocations, and the underlying funds in which it invests at any time, although we expect these changes to be infrequent and generally in response to longer-term structural changes (i.e., in the average retirement age or life expectancy) that lead the fund’s portfolio managers to determine that a change is advisable. We assume investors will begin gradual withdrawals from the

fund at around the target date. Near the end of the target date year, the fund’s target allocations will correspond to those of Putnam Retirement Advantage Maturity Fund (Maturity Fund), a fund that seeks as high a rate of current income as Putnam Management believes is consistent with preservation of capital, and the fund will be merged into Maturity Fund. More information about Maturity Fund is available in this prospectus beginning on page 74, and more information about the underlying funds (which are not offered by this prospectus) is included under “What are the funds’ and each underlying fund’s main investment strategies and related risks?”.

It is important to understand that you can lose money by investing in the fund. Losses may occur near, at or after the target date. There is no guarantee that the fund will provide adequate income at and through an investor’s retirement.

The fund’s allocation of assets among asset classes and the underlying funds may hurt performance.

The fund invests in underlying funds and indirectly bears expenses related to the underlying funds. However, Putnam Management has contractually agreed to waive fees, reimburse expenses of, or reimburse the fund through at least December 30, 2025 in an amount equal to the fund’s acquired fund fees and expenses (i.e., the fees and expenses incurred by the fund as a result of its investments in the underlying funds). Putnam Management also has contractually agreed to waive fees and/or reimburse expenses of each class of shares of the fund through at least December 30, 2025 in an amount sufficient to result in total annual fund operating expenses for class A, C, R, R3, R4, R5, R6 and Y shares of the fund (exclusive of certain fees and expenses, including distribution fees (12b-1 fees)) that equal 0.55%, 0.55%, 0.70%, 0.70%, 0.70%, 0.55%, 0.45%, and 0.55%, respectively, of the fund’s average net assets. Although Putnam Management serves as the investment adviser of the underlying funds, an underlying fund may change its investment program or policies without the fund’s approval, which could require the fund to reduce or eliminate its allocation to the underlying fund at an unfavorable time.

The fund also bears the following risks associated with the underlying funds:

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the underlying funds will produce the intended outcome or that the investments we select for the underlying funds will perform as well as other securities that were not selected for the underlying funds. We, or the underlying funds’ other service providers, may experience disruptions or operating errors that could negatively impact the underlying funds. If the quantitative models or data that are used in managing an underlying fund prove to be incorrect or incomplete, investment decisions made in reliance on the models or data may not produce the desired results and the fund may realize losses.

An underlying fund’s allocation of assets among asset classes may hurt performance. The value of investments in the underlying funds’ portfolios may fall or fail to rise over extended periods of time for a variety of reasons, including general economic,

political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the underlying funds’ portfolio holdings. The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the underlying funds invest and exacerbate other risks that apply to the underlying funds. These effects could negatively impact the underlying funds’ performance and lead to losses on your investment in the fund. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. These risks are generally greater for small and midsize companies.

Bond investments are subject to interest rate risk, which is the risk that the value of the underlying funds’ bond investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the underlying funds’ bond investments may default on payment of interest or principal. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds (sometimes referred to as “junk bonds”), which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Default risk is generally higher for non-qualified mortgages. Mortgage-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. The underlying funds may have to invest the proceeds from prepaid investments, including mortgage- and asset-backed investments, in other investments with less attractive terms and yields.

The value of international investments traded in foreign currencies may be adversely impacted by fluctuations in exchange rates. International investments, particularly investments in emerging markets, may carry risks associated with potentially less stable economies or governments (such as the risk of seizure by a foreign government, the imposition of currency or other restrictions, or high levels of inflation), and may be or become illiquid.

Real estate investment trusts (REITs), which pool investors’ funds for investment primarily in income-producing real estate properties or real estate-related loans (such as mortgages), are subject to the risks associated with owning, operating, and financing real estate, including economic downturns that have an adverse impact on real estate markets. Convertible securities combine the investment characteristics of bonds and common stocks and include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk.

Putnam Dynamic Asset Allocation Equity Fund and Putnam Short Term Investment Fund may use, and each other underlying fund typically uses to a significant extent, derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and investment purposes (although, in the case of Putnam Short Term Investment Fund, they do not represent a primary focus of the fund). Underlying funds that use derivatives to increase investment exposure are riskier than underlying funds that do not employ investment leverage. The value of derivatives may move in unexpected ways due to unanticipated market movements, the use of leverage, imperfect correlation between the derivative instrument and the reference asset, or other factors, especially in unusual market conditions, and volatility in the value of derivatives could adversely impact the underlying fund’s returns, obligations and exposures. Derivatives are also subject to other risks, including liquidity risk (e.g., liquidity demands arising from the requirement to make payments to a derivative counterparty), operational risk (e.g., settlement issues or system failures), and legal risk (e.g., insufficient legal documentation or contract enforceability issues). Derivatives also involve the risk that an underlying fund may be unable to terminate or sell derivatives positions when it wants to and that the other party to the instrument may fail to meet its obligations. The risk of a party failing to meet its obligations may increase if the underlying fund has significant investment exposure to that counterparty.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.